Mass transfer columns, such as distillation, absorption, and stripping columns, have been provided with various types of trays for vapor-liquid contact purposes. These columns are well known in the art for separation of a multi-component feed stream(s) and are not particularly limited herein. Examples of such columns and trays are described in U.S. Pat. Nos. 4,750,975; 5,120,474; 5,453,222; and 8,066,264, which are incorporated herein by reference.
Typically, a mass transfer column has a plurality of trays horizontally supported in a spaced apart configuration over the height of the column. A typical tray has a deck over which liquid passes from an inlet downcomer section to an outlet downcomer. The typical tray deck has apertures through which ascending vapor may flow and over and/or around which liquid may flow in order to bubble or otherwise force vapor through liquid in cross-current flow.
Design of distillation columns and their associated trays is a balance of overall material throughput (e.g. capacity) and tray/column separation efficiency. Accordingly, it is an object of the invention to improve tray and column capacity without sacrificing, or in the alternative improving, efficiency.
The selection and layout of apertures for trays is guided in part by the above-outlined principles. However, vapor and/or liquid interaction between adjacent apertures on a tray and the effect on efficiency and capacity are not fully understood. U.S. Pat. Nos. 5,468,425 and 5,975,504, which are fully incorporated herein by reference for all purposes, describe aperture layouts and “required” aperture spacings for optimal performance of vapor-liquid contact trays. These patents show triangular patterns of apertures across rows of apertures on the tray and describe required spacings between apertures in the row and spacing between rows. These patents however fail to provide a correct understanding of the interactions between adjacent apertures on the tray and hence the “required” spacings between apertures do not provide optimal tray performance (e.g. capacity and/or efficiency). It is therefore strongly desired to obtain a better understanding of these interactions and provide aperture layouts and spacings which enhance tray performance.
It is further noted that trays are supported within columns by underlying tray supports. Underlying tray supports can interact with apertures in the tray to provide regions of dead space on the trays where there is reduced vapor/liquid interaction. It is therefore strongly desired to better understand these dead spaces on the tray and provide ways of increasing vapor/liquid interactions therein to enhance tray performance.